Mumbai, May 21 -- Hindustan Zinc Ltd is down for a fifth straight session today. The stock is quoting at Rs 629.35, down 0.17% on the day as on 13:19 IST on the NSE. The benchmark NIFTY is down around 0.07% on the day, quoting at 23643.4. The Sensex is at 75121.38, down 0.26%.Hindustan Zinc Ltd has added around 4.07% in last one month.Meanwhile, Nifty Metal index of which Hindustan Zinc Ltd is a constituent, has increased around 2.42% in last one month and is currently quoting at 13186.5, up 0.13% on the day. The volume in the stock stood at 20.51 lakh shares today, compared to the daily average of 78.86 lakh shares in last one month. The benchmark May futures contract for the stock is quoting at Rs 631.25, down 0.07% on the day. Hindusta...